added support for web ; bumped dart_core_sdk version to 1.13.2

lib/router/router.dart

@@ -28,15 +28,26 @@ class ReflexRouterDelegate extends RouterDelegate
   _init() async {
     try {
       await authService.init();
-      loggedIn = await authService.isLoggedIn();
+      bool isAuthenticated = await authService.isLoggedIn();
+
+      // If the access token check failed but we have a refresh token,
+      // try to silently renew before forcing the user back to the login screen.
+      if (!isAuthenticated &&
+          authService.refreshToken != null &&
+          authService.refreshToken!.isNotEmpty) {
+        try {
+          await authService.doRefreshToken();
+          authService.tokenRefresher = TokenRefresher(authService,
+              refreshInterval: const Duration(seconds: 60));
+          authService.tokenRefresher!.start();
+          isAuthenticated = await authService.isLoggedIn();
+        } catch (_) {
+          // Refresh token is expired or invalid — full re-login required.
+        }
+      }
+
+      loggedIn = isAuthenticated;
     } catch (e) {
-      showDialog(
-        context: navigatorKey.currentContext!,
-        builder: (context) => AlertDialog(
-          title: Text('Error'),
-          content: Text('Error: $e'),
-        ),
-      );
       loggedIn = false;
     }
   }